Lack of Trypanosoma cruzi Infection in Urban Roof Rats (Rattus rattus) at a Texas Facility Housing Naturally Infected Nonhuman Primates

The protozoan parasite Trypanosoma cruzi causes Chagas disease, uses kissing bugs as a vector, and is maintained in nature by a variety of wildlife reservoirs. Many natural cases of Chagas disease have been reported in NHP at facilities across the southern United States, where infected vectors and wildlife occur. Infection of NHP with T. cruzi can diminish their value as research models and lead to health problems and death. Identifying the modes of transmission and role of wildlife reservoirs in these facilities is therefore critical to guide interventions to reduce transmission. Here we investigated the role of roof rats (Rattus rattus), the most abundant nuisance species at a primate facility in San Antonio, in the maintenance and transmission of T. cruzi. The hearts and blood from the carcasses of the 145 rats collected underwent 2 independent PCR assays for detection of T. cruzi and other trypanosomes. The 145 hearts and 61 blood samples were all negative for T. cruzi. This population sample of 145 subjects would allow the detection of disease prevalence of 0.020 with a confidence level of 95%. The limited active vector surveillance efforts by our team combined with passive surveillance by facility personnel yielded no kissing bugs during the study period. Our results suggest that roof rats are unlikely to be important local reservoirs of T. cruzi at this facility. Further investigation of transmission dynamics across multiple years and more comprehensive vector surveillance is warranted.